The present invention relates to circuit protective devices, and particularly to automatic electric circuit breakers which are equipped with electronic or solid state trip units having the capability of initiating circuit interruption in response to any one of a plurality of abnormal circuit conditions, such as, for example, overload, short circuit and ground fault.
Inasmuch as current solid state circuit breaker trip units have this capability of responding to a variety of abnormal circuit conditions, it would be most beneficial to know, from a troubleshooting standpoint, which abnormality was responsible for tripping the circuit breaker and interrupting the circuit. That is, a positive indication of which circuit abnormality was present can greatly simplify the search for the problem source, enabling corrective measures to be taken all the sooner. Particularly in the case of industrial applications, a loss of electrical service typically means the curtailment or complete halt on a production operation. Thus, it is highly desirable that a power outage, when it does occur, be rectified in as little time as possible.
It is accordingly an object of the present invention to provide an improved multi-function solid state trip unit for automatic electric circuit breakers.
An additional object of the present invention is to provide a static trip unit of the above character, which includes means for indicating which of the trip unit functions was responsible for tripping the circuit breaker.
Still another object is to provide a solid state trip unit of the above character, wherein the indicating means is operated off the trip unit power supply.
A further object is to provide a trip unit of the above character, wherein tripping of the circuit breaker cannot be prejudiced by a failure of the indicating means.
Other objects of the invention will in part be obvious and in part appear hereinafter.